Twisted tuning and running e85

[04mazdaspeed]

Hey guys, I purchased the e-tune from twisted tuning a few days ago. Havent heard anything yet from Justin. How long roughly did it take to get the custom map done for you guys? I'm in no rush as this car isn't my daily so no big deal but was just curious. Also, I plan on getting a custom e85 tune done as well. I spoke with him about trying to run 100 percent e85 and he said he was willing to try it but hasn't done it yet on the n55. I plan on ordering the stage 2 lpfp but am wondering if I should back off on how much ethanol to run. Only reason for wanting to run 100% is so I don't have to mix but its not that big of a deal either. Whats everyones take on that?

[ShocknAwe]

Not sure about the N55, but on the N54 supplemental fueling beyond a fuel pump is necessary to get benefit from more than about 70% mix. With an upgraded LPFP there is a threshold where the HPFP won't be able to keep up, hence the need for throttle body or port injection systems. You won't know where that is until continually increasing boost, likely on a larger turbo, and trying to match fuel flow to keep AFR in check. Eventually the HPFP will start crashing during pulls, which usually happens before reaching 100% E85 contents.

TLDR; use a mix unless you are going for pie in the sky big horsepower where you really need the octane and huge fuel volumes.

[04mazdaspeed]

So you think I should just stick with a e30 or e40 mix for most power on stock turbo?

[bbnks2]

Originally Posted by 04mazdaspeed

So you think I should just stick with a e30 or e40 mix for most power on stock turbo?

The end-goal will likely be the close to the same between E30 and 100% E85. E30 will net you more boost (less stress on fuel pumps since Ethanol requires 30% more flow) with a few degrees less timing (octane will be lower). E85 will net you less boost (rail pressure will crash at lower rpms if you try to increase boost too much) with more timing (higher octane at over 100aki). The result will probably be a few more peak WHP for the 100% E85 tune and gobs more torque/power down low for the E30 tune that runs more boost. If you keep boost lower like 18-20psi you'd be able to run higher ethanol contents without rail pressure crashing at low rpms.

As discussed in a different thread you posted in, all the gains on a stock turbo N55 are really below 5k rpms. The problem with that is fuel flow rate is rpm dependent. N55 will produce massively more torque than an N54 below 5k rpms which is why N55 has a harder time maintaining sufficient rail pressure.

My custom E30 tune hit 507wtq at ~2700rpms. Peaked 364whp at ~5600 rpms. Several revisions later I should be closer to 380/480, but fueling is still an issue and a LPFP didn't help at all since the issue is at such a low rpm. N54 benefits from a LPFP more because the stock twins produce power later in the RPM band where the fuel pumps are at their mechanical limit instead of being flow restricted due to high boost at low rpms like the n55 power curve.

This isn't well documented yet since few people have pushed the stock turbo past 20psi or so (limit of stock TMAP), but the speculation seems to be accurate so far from my experience. Could also be that the LPFP is struggling to feed the HPFP at lower rpms. I only installed a stage 1 pump. You'd have to ask FuelIt to speculate on whether a stage 2 upgrade would flow more at lower rpms than a stage 1 upgrade can. I doubt that's the issue though.

[ShocknAwe]

Another point to keep in mind is your DCT clutch packs will slip eventually at higher wtq. Some custom tuners with N54 DCT cars (I know, different engine, yeah) and upgraded turbos speculate the level is somewhere around 550wtq. Then some others doing fine at around 600wtq. Either way, I'd keep that TQ level down and HP level up to save yourself from needing upgraded clutches, that's $$$.

Some good evidence for what bbnks2 is talking about with ethanol mix tuning.

[The Wind Breezes]

I emailed him about this exact question. Here are the details:

1) you'll need the LPFP upgrade for sure so good on you for planning on that
2) E85 will make *some amount* more power than E30 for sure, it will all be through timing as the turbo is already maxed out up top and torque is limited at low RPM anyway for stock rod reliability. I wasn't given an actual number for the power increase up top, but there will surely be some over E30 particularly since you're getting a custom tune. Simplified, E85 lets you advance timing all the way to optimal on a stock turbo, E30 mix does not. This power increase is probably not that much in the scheme of things, and I doubt you would see, say, an honest 400whp or close to it but who knows? Full E85 never been done justice on N55, to my knowledge.
3) The DCT can take a whole lot of torque, I was told they have cars running over 600lbft on stock DCT. As mentioned torque has to be limited down low anyway as a result of fueling constraints and the stock bottom end, so you probably won't be slipping the DCT unless you try to launch on really sticky tires. That is where people have run into trouble. Even stock power with slicks could be troublesome, if the wheels don't break free, because the clutch hardware heats up real fast when slipped a lot (what it's forced to do when you launch and the tires hold). Also, I was told to always use sport mode with upgraded power because it shifts more firmly and slips less.
4) Unless you're really interested in the data, just get an upgraded turbo because the gains are marginal for the effort involved
5) Please do this because personally I'm rather curious

[04mazdaspeed]

Thanks for the responses guys. The more I think about it, I think a mix is probably in my best bet. I'm thinking e30 or maybe e40 with the upgraded pump. I will email fuel it and ask them about the added fueling at low rpm. The car isn't my daily so I would hate to run 100% and start having problems and it would take me forever to drain the tank...lol I truly find the car a blast even on the e30 ots tune. Much more power past this isn't really needed but more power never hurt..lol I do eventually would like to go ps2 just to get the car around 500whp then wrap it up around there. For now though, I would just like to enjoy a slight more power increase especially torque since I'm usually cruising around 3k anyways. Also, I'm not launching the car so I'm not too worried about the dct slipping. I'm still on the stock run flats(been replaced since new but not by me). I always use sport mode unless I feel like driving like a granny which isn't too often. Still waiting to hear back from Justin about starting to tune. I'm not in a huge rush but its been a week now and still haven't heard anything which is making me anxious.

[04mazdaspeed]

Also, whats been the limit of the stock bottom end? Obviously it could go whenever but whats usually the safe limit to preserve it?

[bNks334]

Originally Posted by 04mazdaspeed

Also, whats been the limit of the stock bottom end? Obviously it could go whenever but whats usually the safe limit to preserve it?

Not too many documented n55s over 600whp yet. There is no reason why it shouldn't hold as well as an n54 though.

[The Wind Breezes]

Originally Posted by bNks334

Not too many documented n55s over 600whp yet. There is no reason why it shouldn't hold as well as an n54 though.

Power doesn't matter as much as torque, and the torque is more harmful the slower the engine's spinning because the faster you rev the more the rod is being "pulled" to counteract the force on it from the bang in the cylinder. That's why they limit torque down low...the tiny turbo can make a whole crapload down there but it wouldn't be safe. The crankshaft is another issue, but in reality they're pretty strong even though people bitch and moan about them being cast--yeah, sure, but they're cast from a high end ductile iron with an advanced process. The longer a crankshaft is, the more issues you have with twisting, and this isn't the shortest crankshaft in the world, but it doesn't seem to be something that breaks.

As far as numbers, let's say you're making 600 ft*lb torque to the wheels at 7000 RPM with a big turbo. That would be nearly 800 WHP. Power = torque * RPM / 5280.